I know lithium are the only reliable ones for cold weather, they are also lighter and last longer than other types - however are a little more expensive.

I bought some NiMH rechargables today (energizer e^2), not sure if I want to keep them or not as I've never packed with rechargables. I usually just buy a big package of standard alkalines. Probably better environmental wise for the rechargables, but I am concerned with performance. I"ve read rechargables do not put out the voltage as lith/alka so lights may not be as bright (like .5ish volt difference?).

I'm fairly sure lithium would be best weight/performance, but at a price ($). What does everyone use?

I have two kits of rechargeables made by Sanyo and sold under the brand name "Eneloop." The kit has 8 AA's, 4 AAA's, plastic sleeves to use the AA's as a C or D size and the charger.

I have found the AA's last a long time. I have used them in my Canon digital camera, which takes 4 of them and even in cold weather, they will take a lot of pictures. I carry a set of alkalines as spares, but rarely have needed them. I haven't really tested the AAA's, but presume they'll last about as long as an alkaline, but if not, I'm not too worried.

I like the idea of rechargeables. I use them around the house and haven't bought batteries, except as backups, in ages.

They may not put out the same voltage, but I haven't really noticed. Some devices may be more sensitive than others to the voltage issue, but none that I have.

Go with lithium unless your headlamp/flashlight does not recommend them. Yes, they are more expensive, but they provide almost 3x the runtime of alkaline cells. Buy them online in bulk to save some money. With a 10-year shelf life, they'll last long enough for you to use them all. It costs me $1.50 per cell, and I'll almost burn through 2 in a weekend on the trail (see my user name). Using NiMh, I would go through 4-6 depending on the temperature. That's a savings of 3-5 ounces by shifting to lithium (substitute 2 batteries and add 2-4 more). On a week-long trip the weight savings are obvious.

I'm not including NiCd because that's a dead technology - NiMh is superior in all respects. Alkaline is by far the worst for high-current applications. If you're using a 1W or more lamp, alkaline will have the least capacity of the 3 battery chemistries, even though it's rated midway between NiMh and lithium. As you can see, NiMh is the heaviest of the batteries while lithium is the lightest. You save about an ounce by swapping two AA lithium cells for NiMh.

NiMh is the "greenest" of the batteries because of the re-use factor. You can expect about 50 recharges over 2 years before cells get to the 75% point (they only take 75% of a new cell's charge). I know they say 500 or more, but this is reality. My experience has been that 2-year-old batteries have about a 20% failure rate too - where the battery refuses to charge again. Buy a good charger if you decide on NiMh - one that charges each cell individually. Chargers that only charge 2 cells at a time will result in unequal charging in the cells, which leads to premature battery failure.

Since NiMh have an open-circuit voltage of 1.2 v, some applications are unsuitable. Using them in incandescent flashlights will yield a dimmer, yellower light. In LED applications their suitability depends on the circuitry. A fully regulated light will usually perform just fine. In many cases even the unregulated lamps perform at an acceptable level. I can tell you that the Princeton Tech EOS is one that does NOT like NiMh batteries, with very short run times before the light goes into unregulated mode. Cheapie single-cell headlamps from Target and Walmart seem to be indifferent to the type of battery installed, varying only in runtime.

What do I use now? A lithium-ion battery pack that powers all my electronic toys and charges the flashlight batteries. This gives me the benefits of lithium's high energy density with rechargeability.

Flashlights and electronics place different loads on batteries. You can get away with alkalines in LED flashlights for literally a tenth of the cost of disposable lithiums, and I've been able to go through an entire summer on a single set.

Electronics like GPSs and digicams don't match alkaline discharge curves well, and give limited battery life. NiMH and lithiums perform much better. I'll splurge for lithiums for my GPS for weeklong trips, otherwise I use NiMH exclusively. One of the best features of rechargeables is knowing you're leaving with a full charge every time. Lithiums are far too expensive to throw away partially used, and I have a tough time keeping track of how much life is left in a given set. They're a bit like stove cartridges in that respect, except you can't weigh them.

The Eneloops are good to carry as spares, since they don't self-discharge quickly, but are lower capacity than standard NiMH. I leave with my highest capacity batteries in the GPS (3000 mAh) and pack a pair of Eneloops (2000 mAh) as spares.

Most of my headlamps are AAA, so there's no cross-sharing with the GPS.

I know lithium are the only reliable ones for cold weather, they are also lighter and last longer than other types - however are a little more expensive.

I bought some NiMH rechargables today (energizer e^2), not sure if I want to keep them or not as I've never packed with rechargables. I usually just buy a big package of standard alkalines. Probably better environmental wise for the rechargables, but I am concerned with performance. I"ve read rechargables do not put out the voltage as lith/alka so lights may not be as bright (like .5ish volt difference?).

I'm fairly sure lithium would be best weight/performance, but at a price ($). What does everyone use?

I get my generic AA alkalines for 25˘. I wait until I see sales. These have about a 5% lower capacity than Duracell who are 2-3x more expensive. Except there is one generic brand that is terrible: Stay away from batteries.com. I wonder if they aren’t really selling carbon-zinc batteries (disguised as alkaline).I get my Energizer lithium AA from Sam’s club for $1.67 each. I tried the generic lithium’s on the internet for $1.00. I thought “wow. Good price.” But they only go for ˝ as long as the Energizer Lithium.

I’ve tested Sanyo, Kodak, Energizer, and Duracell 2500mAH NiMh AA batteries. Kodak has lasted the longest by taking the most charges (approaching 250 on my count) and they last the longest (per charge) of all 4 brands in my flashlight.

I use my Fenix L1D flashlight every day of my life (biking, backpacking, work). On high, the lithium AND the NiMh go for 140 minutes (stay bright before dimming). Yes, both get the same time (maybe Lithium gets 2 minutes more). You can see how the rechargeables save money. I only use the Lithium backpacking since they are lighter. I use the NiMh for all other times; that is an incredible money savings.

Rechargeables are great for flashlights that hold a constant output (like Fenix). 3-Cell lights tend to do poorly with rechargeables (compared to lithiums) because they rely on the battery voltage more than the energy left (like a Fenix). Again, out backpacking, I use Lithium to save weight and it does better than NiMh in colder weather. You would have to take four alkalines to equal the runtime for one lithium. That’s too much extra weight and bulk. Plus alkalines do extremely poor in cold.

If I was only using my flashlight once/week, I would switch back to Lithium’s since NiMh still have a higher self-discharge rate and who wants to be caught w/ a dead battery?

For cold weather, NiCd is the best, followed by Lithium and then NiMh. Alkalines--- just don’t take them!

Now if we could just get a 2500mAHr AA NiCd (1000mAHr max today), we would have an awesome runtime rechargeable for all temperatures.

Some GPS’s have a battery software switch to let you switch between rechargeable and alkaline. This way the battery warning doesn’t come on too soon.

If using NiMh, make sure your charger has –dV/dT technology. This will shove a constant current through your battery. The battery will then hit somewhere between 1.38 and 1.42V and then start dropping (even though constant current is being applied). When the battery dips, the charger will then completely cut off the current (no trickle charging allowed for NiMh or their life is cut). The faster chargers will also monitor temperature so they can crank up the current w/o killing the battery.

Another type of charging that Toyota Prius uses is: just charge it to 90% capacity. In theory the battery will last forever. I’m still testing this and I’m at 192,471 miles; and so far--- they’re right.

Any other type of charger will shorten the # of charges your NiMh can take.

“I'm not including NiCd because that's a dead technology - NiMh is superior in all respects.”

Hello Niyty,I think NiCd will stay alive for a while since it has the BEST drain performance of NiMh, Alkaline, and Li. Mainly because they have the lowest internal resistance (by far). R/C airplane enthusiasts love that. And they’re still kicking in the power tool segment. And they’re much easier to charge because it is very forgiving of overcharging and thus uses a cheaper charger. This is also why the most popular solar cell setups use NiCd. NiMh need the more elaborate –dV/dT w/ cutoff chargers to get the most charges out of them (which I have tested for the last 3 years). Also NiCd ends up giving the lowest cost in A-Hr/1000-uses.

True, I wouldn’t use them right now because I can get more runtime with the 2500mAh NiMh or a Lithium AA in my flashlight. But if you don’t mind changing the batteries out more often, this would be the lowest cost choice (for battery and charger).

I just didn’t want to count out my babies <img src="/forums/images/graemlins/tongue.gif" alt="" />.-Barry

Nicads still have their niche. Open up any of the newer solar powered garden lights and you'll find them there. Home Depot still sells replacements. They are more robust than NiMh because they can tolerate overcharging and deep discharging better. They also have a lower self discharge rate than all but the newer LSD (low self discharge) NiMh cells.

Personally I prefer rechargeable cells over primaries. I like to keep landfills as small as possible. There are rechargeable lithium-ions out there now than can replace AA'a and AAA's under certain conditions. Best of all worlds. And they are not too expensive any more.

_________________________If you only travel on sunny days you will never reach your destination.*

I suppose there are still a few niche markets for NiCd technology. I never even thought of RC cars - you're right about those, although NiCd is being replaced by LiPo technology (lighter, 20C discharge rates, lighter = faster, high energy density, did I mention lighter?).

As far as the ultimate in battery tech - I'm still waiting for those promised methanol fuel cells. Panasonic said in 2006 that they would be putting them in laptops and cell phones by the end of 2007. Now we're over half-way through 2008 and they still haven't shown. Imagine something the size of two Cricket lighters side-by-side that has an 8000 mah capacity on one lighter's worth of fuel. That's the kind of power source that make a tech-head like me wet my britches! I bet a 99-cent bottle of Heet would keep my laptop running for weeks.

The coolest energy tech that's still quite a ways away from leaving the lab is implantable batteries that use biotech from animals like the electric eel to generate electricity. Eh, but then you're trading batteries in your pack for extra food. Maybe not so hot an idea for hiking?

Yes I agree with TomD that the Eneloop batteries are good. In fact they are so good that I have switched completely to them.

I have two "tests" that convinced me. The first was in a new gps. According to the gps producer the batteries should last 20 hours. We started skiing and I had the gps running on two full days. Temperature was -10C with a breeze blowing all the time. The gps was kept in an open pocket on the thigh, so it was not heated much from my body. Still it worked for 18 hours, and I was astonished.

The second "test" was with a new camera I bought that uses AA batteries. The batteries was new of the brand that the camera producer had included in the package. Whe we started on a skiing trip the battery indicator said full, but after only two hours <img src="/forums/images/graemlins/shocked.gif" alt="" />it was blinking red. I changed to the Eneloop batteries, and we used the camera for the rest of the trip (5 days) with just these batteries. <img src="/forums/images/graemlins/smile.gif" alt="" />

The Eneloop batteries I use are charged in a normal charger. I did not buy a complete set, just the batteries, and it works fine. Here in Norway the Eneloop is not more expensive than other brands, and they are sold 4 in a packet. If any one has trouble with batteries in cold weather I urge them to try these out. They should also keep charging much longer than other brands. According to the producer 85% of the capacity is still left after one year.

There are some nice lights out there that use Li-ion like the Fenix TK11. It gets good runtime. However it’s heavier such that I wouldn’t take it backpacking.

Some small lights that take one CR123 can ‘sometimes’ take a rechargeable version. You need to double check that the single cell CR123 lights can take the higher voltage (3.7-4.2V) for the Li-ion. And these are lightweight. But in my experiments, I have a Nuwai light that takes one CR123 and goes for 90 minutes on a primary cell. But I put in a protected Li-ion CR123 battery and I only get 40 minutes. So the short life hasn’t appealed to me (because I don’t want to keep swapping out batteries in the field).

“Anything particular I should look for in a quality charger as well?”

So far as I have seen, there are no bad commercial Li-ion chargers. However, there are 2-types of Li-ion CR123’s (sometimes called R123’s); the ‘protected’ and ‘unprotected’. Just make sure you get the matching charger.

If you find a small lightweight light that gets good runtime using Li-ion, LET ME KNOW. Thanx!

If you want small and rechargeable, right now, the single cell AA lights seem to get the longest runtime with NiMh.

I want to thank whoever it was (in a long thread some months back) who put me on to Eneloop batteries. They are great--definitely last longer than alkaline batteries. They also, of course, keep used-up batteries out of the landfills.

My problem was specifically my camera, a Canon A710, which was eating batteries like there's no tomorrow--I could use up a set of alkalines in a day. Per the instruction book and the Canon website, lithium batteries are a no-no for this camera. I have solved the problem--there is a power-saver feature on the camera so I can turn off the LED screen and use the viewfinder. Of course I've had to make some adjustments for parallax and for the fact that what the viewfinder shows is a little smaller than the actual picture (I've had to use software editing tools more). But with the LED screen turned off and freshly charged Eneloop batteries, I went through a 7-day trip, taking LOTS of pictures, with only one set of batteries.

However, the spare Eneloop batteries I took (and didn't need) required about 6 hours to recharge after being exposed to temperatures close to freezing without any insulation. I suggest keeping the camera (or whatever you're using the Eneloops in) and extra batteries well wrapped up inside your pack at night.

_________________________
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey

I have used the same maha powerex 2700 rechargables for a few years in a couple of different AA Canons, headlamps etc.. They have work really well. I have ordered from Thomas Distr. a few times, a good company.

I have been using AA rechargeables for years in my Underwater cameras and strobes, 1st NiCad now NiMHs. I will take 2 dozen on my trip to Cozumel in Oct. I will use 12 - 24 batteries / day, and have used up to 36 batteries on a live-aboard dive boat where I do up to 5 dives per day. In my case, rechargeables are a must, from a cost and environmental standpoint. I have purchased the Maha PowerEX from Thomas on several occasions and both are good.

NiMH work great for this application because they go from charger to gear to charger. However, they are not good for holding a charge and their daily loss 1% / day is pretty high compared to Li-Ion. Li-inons supposedly loose less than 3% / month. I was very happy with the battery life of my Canon G9 and Canon Li-Ion batteries on my GC trip. Consequently, I took more battries than necessary and will learn from my experience.

Edited by scottyb (09/30/0811:19 AM)

_________________________
Just because you don't take an interest in politics doesn't mean politics won't take an interest in you.... Pericles (430 B.C)

NiMH work great for this application because they go from charger to gear to charger. However, they are not good for holding a charge and their daily loss 1% / day is pretty high compared to Li-Ion. Li-inons supposedly loose less than 3% / month.

Maybe that was so before, but there are NIMH that looses only 1% per month. http://www.eneloop.info/218.html In addition these batteries function better even in severe cold weather, and that is an enormous advantage for me. Dont know how many great pictures I've lost becuse the f... proprietory batteries of the former camera i had (Li-ion type) were flat. Yes I had a spare battery with me, but that too had said goodbye. They both were fully charged befor the trip.

What did I do? Well there is a very warm spot close to your body and some intimate parts <img src="/forums/images/graemlins/blush.gif" alt="" /> . This is funny to tell about, but to walk with the battery there is NOT funny. But after a trip to a glacer near by, I did not get a single picture from the trip. After that it was goodbye nogood Li-ion for me.

One more advantage: Price. I can buy 20 Eneloop batteries instead of 1 to the mentioned camera. /Otto

Hey, now that's good info Otto.. I've seen then eneloops before, looked at the mAh ratings and kinda shrugged and thought "what's the big deal" - but I hadn't actually seen the part about the discharge rate!.. That makes them enormously more useful for me ina couple of things - might just have to go buy me some of those.. Thanks!

I have used low discharge Eneloops in my GPS and other high capacity NiMH batteries in my camera strobes and they have performed great.

NiMH batteries are lower voltage, 1.2V rather than 1.5V so you do need to check with the manufacturer of your electronics gear for compatibility. Some devices have a switch for use with NiMH and some will not work correctly at all.

I have a Petzl headlamp that will not work with NiMH. It appears to work and is very bright when you first turn it on but goes dim after only a a few minutes which is very deceiving if you just turn it on quickly for a quick function check before throwing it in your pack as I found out on my first trip with NiMH batteries.

Can you buy just AA Eneloops? I always see the full kit with the C, D, and AAA charger cells but I only use AA's. Where are there good deals on these? Can they be charged in a different brand charger for the AA's? Thanks <img src="/forums/images/graemlins/smirk.gif" alt="" />

If you're dead set on Eneloops, fine. But there are other brands of low self discharge cells out there. Eneloops do seem to test out as the best(sometimes barely) but they are more expensive. I've also had good luck with Duracell and Kodak from Wally World.

Eneloops are still NiMH cells like any other in that regard. The basic chemistry is the same. Therefore any charger designed for NiMH will charge them.

But......I highly recommend a quality "smart" charger over a cheap "dumb" charger. Overcharging is a cell's worst enemy (along with overdischarging) and those "dumb" chargers just don't know when to quit. Whereas the "smart" chargers use voltage and temp. sensors to terminate the charge cycle. Some will even "refresh" your old tired cells and give them a new lease on life.

I personally prefer chargers that work on individual cells as opposed to pairs only. I have FRS radios and headlamps that operate on 3 cells. I also have lights that operate on one cell.

Do some reading at Thomas Distributing. They sell a huge variety of smart chargers.

_________________________If you only travel on sunny days you will never reach your destination.*

Seeing as there are 5 different brand AAs from the looks of it over at Thomas; has there been any brand testing? Are they all the same formula in different wrappers, or are some noticably worse at holding charges than others?

I think one of these is a smart investment. I have one (Powerex MH-9000) that handles as many as four batteries individually, and charges, refreshes and analyzes, breaks in, discharges and cycles. It forms new batteries for maximum performance, gives detailed capacity ratings for matching battery sets, brings back old batteries from the graveyard and restores maximum performance to older batteries. It allows me to match each of these functions with the specific battery capacity.

It only handles AAs and AAAs and wasn't cheap, but with the proliferation of rechargeables has proven invaluable.

Geeze my Sanyo only charges 4 at a time then the green light comes on and the red one goes off <img src="/forums/images/graemlins/tongue.gif" alt="" /> I have seen some of the Eveready, Duracell AA chargers in stores, even one that you can use from a vehicle's cig lighter plug <img src="/forums/images/graemlins/shocked.gif" alt="" /> or wall socket. Hard to tell which of these would be worth spending money on since I have a battery charger now <img src="/forums/images/graemlins/confused.gif" alt="" />

I have a Maha MH-C801D http://www.thomas-distributing.com/maha-...CFQVxFQodmGS4LA . I paid a little over $100 for mine a couple of years ago. While it only charges AA's and AAA's, it is the best charger that I have ever had. I bought it primarily to charge AA's for use in my DSLR and flash but I have switched just about all the battery-powered devices to rechargables now. Everything from remotes and my computer mouse to flashlights and my GPS.